A typical vehicle or work machine includes a battery that provides power to the internal combustion engine and the onboard electrical systems of the vehicle or work machine. Because the battery is constantly providing power to both the electrical systems and engine, the battery charge is constantly being drained. Thus its voltage output constantly drops. However, when the engine is running, a battery charging system (i.e. alternator or other power electronics) recharges the battery such that the battery charge is high enough for continued power output, and will remain high enough to start the engine on the following startup attempt.
Battery temperature is an important parameter for controlling battery charging or discharging processes. Knowledge of the battery temperature will enable the processes ability to prevent the battery from overheating at high temperatures during charging or discharging, and also prevent the battery from being overcharged at low battery temperatures during charging.
Conventionally, a battery temperature sensor is mounted outside of the battery, usually under the battery tray upon which the battery is mounted, for measuring the battery temperature. Because the temperature sensor is mounted outside of the battery, the temperature measurement is affected by the surrounding environment, and therefore does not accurately reflect the dynamic variations of the battery's internal temperature. The inability to accurately determine a battery's internal temperature adversely affects the battery charging and discharging strategies.
Implementing an externally mounted temperature sensor in the system is detrimental to the system effectiveness because of the inability of the sensor to accurately determine a battery's internal temperature and a significant addition of cost due to the sensor. The cost addition results from the sensor device hardware and the installation labor to the vehicle or work machine. It is impractical to incorporate a temperature sensor within the battery itself because of the costs involved, the design requirements of the battery, and the fact that the battery is often replaced by a user. Therefore, it would be beneficial to provide a more reliable, more accurate and cost effective technique for approximating the battery temperature.
One method of determining a vehicle battery temperature without installing a battery temperature sensor is described in U.S. Pat. No. 6,076,964 (the '964 patent) issued to Wu et al. The '964 patent describes a model for determining a battery temperature by using several physical measurements on the vehicle. However, the system of the '964 patent only measures the heat transfer from an engine to the battery due to the mechanical attribute of the engine to the battery, and neglects the heat generated in the battery due to the chemical reactions that take place during charging and discharging of the battery. Therefore, it fails to provide an accurate approximation of the internal temperature of the battery.
The system of the present disclosure solves one or more of the problems set forth above.